Radio tuning device



Dec. 31, 1940. J. w. FITZ GERALD RADIO TUNING DEVICE Filed May 10, 1937 2 Sheets-Sheet l D. M n

Dec. 31 1940.- J. W/FITZ GERALD 7 2,226,858

RADIO TUNING DEVICE Filed May 10, 1957 2 Sheets-Sheet 2 Patented Dec. 31, 1940 PATENT OFFECE RADKO TUNING DEVICE John W. Fitz Gerald, Milwaukee, Wis, assignor to Briggs & Stratton Corporation, Milwaukee, Wis, a corporation of Delaware Application May 10,1937, Serial No. 141,686

'7 Claims.

This invention relates to improvements in radio tuning dials and refers particularly to the socalled automatic tuning devices of the type shown in Patent No. 1,744,265 issued to John W. Fitz Gerald, January 21, 1930.

These devices, as shown in said patent, generally comprise a plurality of movable stops con nected with the tuning element of the radio receiver to provide means for adjusting the same and selectively operable to positions engageable with a stationary stop to arrest the adjusting motion at definite points.

Inasmuch as the tuning element of a radio receiver turns through only one hundred and eighty degrees, rotation of the dial in both directions is necessary and consequently, when tuning the same station, the movable stops are at times engaged with one side of the stationary stop, and at other times with the opposite side of the stationary stop. This condition precludes accuracy as the stationary stop and also the movable stops have thickness preventing the tuning element from being brought to the same position in each instance.

It is therefore an object of this invention to provide cooperating movable and stationary stops so related that regardless of whether the movable stops are engaged with one side or the other of the stationary stop, the tuning element is always brought to the same desired definite position.

More specifically, it is an object of this invention to provide a self-adjusting stationary stop which has a limited degree of motion with the movable stop upon engagement of a movable stop therewith, to arrest the adjusting motion of the tuning element at a definite point regardless of whether the movable stop is engaged with one side or the other of the stationary stop.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it be--- ing understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two two complete examples of the physical embodiment of the invention constructed in accordance with the best modes so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a front view of a radio tuning dial of the type to which this invention appertains;

Figure 2 is a vertical sectional view taken through Figure 1 on the plane of the line 2-2;

Figure 3 is a detail sectional view taken through Figure 2 on the plane of the line 33;

Figure 4 is a vertical sectional View similar to Figure 2, but illustrating a slightly modified embodiment of this invention; and

Figure 5 is a detail sectional view taken through Figure 4 on the plane of the line 55.

Referring now particularly to the accompanying drawings in which like numerals indicate like parts throughout the several views, the numeral 5 designates the chassis of a radio receiver which is generally mounted in back of a front panel 6 and which includes a tuning element i usually in the form of a variable condenser or gang of condensers. The tuning element l is adjustable by means of a rotatable shaft 8 for tuning the receiver to any desired broadcasting station within the frequency range of the receiver.

The shaft 8 projects forwardly toward the front panelfi where it is connected with a dial mechanism, indicated generally'by the numeral 9. This dial mechanism may be of any desired construction and in the present embodiment incorporates a pointer It rotatable with the shaft 8 to cooperate with indicia (not shown) delineated on the face of the dial to indicate the position of the tuning element, and consequently, the frequency to which the receiver is tuned.

Normal manual adjustment of the tuning element is eflected by a rotatable knob H which projects upon the face of the front panel and is drivingly connected with the shaft 8 by means of a pulley l2 and a cable I? trained about the pulley l2 and about the periphery of a disc 14 fixed to the shaft 8 by means of a bracket 55. It is thus possible to adjust the tuning element to any position within its one hundred and eighty degrees of rotation in the conventional manner, and as will be readily apparent, the relatively large difference in the diameters of the pulley enabling fine adjustment of the tuning element.

The tuning element is also adjustable quickly and directly to any one of a number of definite positions to provide the so-called automatic tuning. For this purpose, a rotatable ring 15 encircling the dial face is fixed to the disc 14 by posts ii so that rotation of the ring l6 directly drives the shaft of the tuning element. The ring Hi carries a plurality of station selecting devices, indicated generally by the numeral IS. The deand the disc Hi provides a large gear reduction tailed construction of these station selecting devices may be of any desired design and in the present instance follows the disclosure of the aforesaid Patent No. 1,744,265.

Each station selecting device consists of a button l9, the face of which has the call letters of a particular broadcasting station delineated thereon to be visible through finger holes 20 in the ring which also provide means of access to the buttons l9. Each button is mounted on a stem 2| which is threaded into a bushing 22 fixed to a spring segment 23 clamped to the back of the disc I4. A lock nut 24 threaded on the stem 2| provides means for securing the same in a definite position of rotational adjustment.

On the inner end of the stem 2|, an arm 25 is secured to eccentrically mount a stop 26 from the stem. This manner of mounting the stop 26 permits adjustment of its position circumferentially with respect to the ring l6 and the resiliency of the spring segment 23 permits the entire assembly to be depressed inwardly by inserting a finger through the hole 20. Inward depression of the selector assembly moves its stop 26 rearwardly from its normal inoperative position into the plane of a stationary stop 21 so as to be engageable therewith upon rotation of the ring l6 and consequently, the tuning element.

Obviously, such rotation is limited at a definite point by the engagement of the stop 26 with the stationary stop 21 and the specific location of this point is dependent upon the individual adjustment of the stop 26, this adjustment being such that the tuning element is brought to the proper position upon the engagement of the stop 26 with the stationary stop 21 to tune in the station delineated on the selected button 19.

To insure the proper disposition of the tuning element regardless of whether the stop 26 is ened with one side or the other of the station ary stop 21, the stationary stop 21 is mounted to have a limited degree of motion with the movable stop. To obtain this limited motion, the stationary stop 2'! may be mounted as illustrated in Figures 2 and 3, or as shown in Figures 4 and 5.

In the former, the stop 21 has an I shape and the ends thereof have parallel slots 28 disposed at right angles to the major or longitudinal axis of the stop which is parallel to its side edges. The slots 28 are of the same length and extend equal distances beyond opposite sides of this axis. The stop is mounted by retaining screws 29 which pass through the slots 28 and are threaded in posts 30 mounted on a fixed bracket 3 I. The disposition of the screws 29 is such that they hold the stop in a position at which either of its'side edges are engageable by the stops 26 regardless of their positions of adjustment; and as clearly shown in Figure 3, the proportions of the parts are such that the center of any selected stop 26 is brought to the same vertical plane regardless of whether it is engaged with one side edge or the other of the stop 21.

In the embodiment illustrated in Figures 4 and 5, the stationary stop 21 takes the form of a pivoted lever 32 mounted to swing on the axis of the shaft 8. The lower free end portion of the lever provides the stop per se and the motion limiting means consists of a transverse slot 33 in the 3 lever and a pin or screw 34 disposed in the slot and threaded in a post 35 mounted on a fixed bracket 36.

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention provides simple means for insuring the accurate disposition of the tuning element of a radio receiver with so-called automatic tuning regardless of whether the tuning element is turned in one direction or the other.

What I claim as my invention is:

1. In a tuning device for radio receivers having a rotatable tuning element: means for quickly adjusting the rotatable tuning element to a definite position to which the receiver is tuned to a particular broadcasting station, including a manually operable stop movable with the tuning element, and another stop engageable by said manually operable stop to arrest rotation of the tuning element; said other stop being formed of a single piece of flat material having an enlarged slotted portion at each end thereof; and means engaged in said slots for limiting said other stop to a degree of motion upon engagement of the stops to insure the disposition of the tuning element at said definite position regardless of from which direction the engagement of the stops is efiected.

2. In a tuning device for radio receivers having a tuning element rotatable about a fixed axis: means for quickly adjusting the rotatable tuning element to a definite position at which the receiver is tuned to a particular broadcasting station, including a manually operable stop movable with the tuning element, and another stop engageable by said manually operable stop to arrest rotation of the tuning element, said other stop having a slotted portion medially of its ends; means at one end of said other stop for pivotally mounting the same formotion in a plane parallel to the tuning element; and means engaging in said slot for limiting said other stop to a degree of motion upon engagement of the stops to insure the disposition of the tuning element at said definite positionregardless of from which direction the engagement of the stops is effected.

3. In a tuning device for radio receivers having a tuning element rotatable about a horizontal axis: means for, quickly adjusting the rotatable tuning element to a definite position at which the receiver is tuned to a particular broadcasting station, including a manually operable stop movable with the tuning element, and another stop engageable by said manually operable stop approaching it from either direction to arrest rotation of the tuning element, said other stop comprising two supports spaced apart on a line radial to the axis of the tuning element, and a rigid member mounted on said supports and having a part engageable by the manually operable stops, and a connection between said rigid member and one of said fixed supports providing for movement of said member and for limiting movement thereof to a degree of motion necessary to have the manually operable stops, and consequently the tuning element, come to rest at exactly the same point regardless of from which direction it approaches said other stop.

4. In a tuning device for radio receivers having a rotatable tuning element: a plurality of station selecting devices selectively operable to adjust the tuning element to a predetermined position at which the receiver is tuned to the station represented by the selected station selecting device; a stop engageable by a part of any selected station selecting device to limit the adjusting motion of the tuning element; fixed abutments mounting said stop; and a connection between said abutments and the stop whereby the stop is capable of a limited degree of translating motion permitting movement thereof in either direction for a distance such that the adjusting motion of the station selecting device is arrested at a predetermined point regardless of from which direction it is engaged with said stop.

5. In a tuning device for radio receivers having a rotatable tuning element: a plurality of station selecting devices associated with said tuning element and movable therewith in an arcuate path; and a stop cooperable with said station selecting devices to halt rotation of the tuning element comprising, spaced abutments, one of which lies radially inside and the other of which lies radially outside of said arcuate path, and a member movably carried by said abutments so as to be capable of a limited degree of translating movement in a plane normal to the axis of said tuning element, said member lying in said arouate path so as to be engageable by any selected station selecting device for arresting rotation of the tuning element at a predetermined point regardless of its direction of rotation.

6. In a tuning device for radio receivers having a rotatable tuning element: a dial part connected with the tuning element to be rotatable therewith; a plurality of station selecting devices associated with the dial part, each including a depressible stop abutment adapted to be moved to an operative position; a radially disposed stop member lying in the path of any stop abutment in operative position to be engaged thereby either on one side or the other, depending upon the direction of rotation of the dial part; spaced radially disposed abutments; and a connection between the stop member and the abutments providing the stop member with a limited degree of motion in a plane normal to the axis of the rotatable tuning element to permit the disposition of an operative stop abutment and consequently the tuning element in a predetermined position regardless of from which direction the engagement between the stop abutment and the stop member is effected.

'7. In a tuning device for radio receivers having a tuning element rotatable about a fixed axis: means for quickly adjusting the rotatable tuning element to a definite position at which the receiver is tuned to a particular broadcasting station, including a manually operable stop movable with the tuning element, and a substantially stationary stop having a part engageable by the movable manually operable stop to arrest rotation of the tuning element and having an opening providing transversely spaced abutment portions, said part being substantially radially disposed With respect to the axis of the tuning element; means mounting said substantially stationary stop for pivotal motion about an axis spaced from its transverse opening for motion in a plane normal to the axis of thetuning eleless of the direction of rotation of the tuning ele- 9 ment, said fixed means being of such proportions with relation to the space between the abutment portions as to arrest pivotal motion of the substantially stationary stop at points such that the engaged side edge of its stop engaging part is in position to arrest motion of the tuning element atsaid definite position regardless from which direction the engagement of the stops is effected.

JOHN W. FITZ GERALD. 

